Hydraulic hammers are used at work sites to break up large and hard objects before such objects can be moved away. Generally, hydraulic hammers are coupled to machines, such as excavators or other machines. A hydraulic hammer includes a piston that is moved against a volume of gas in an accumulator coupled to a power cell of the hydraulic hammer, thereby compressing the volume of gas. The compressed volume of gas further facilitates downward movement of the piston. As such, the accumulator needs to be charged by the gas at a desired pressure. Usually, the gas inside the accumulator can only be checked but not refilled. Charging the accumulators of the hydraulic hammer without knowing actual pressure of the gas may lead to higher operation cost as charging of the accumulator is expensive and complex.
U.S. Pat. No. 7,356,990 (the '990 patent) discloses an electro hydraulic actuator with built-in fail safes. Multiple accumulators are integrated into the actuator to improve reliability and redundancy. One or more accumulators can fail and the remaining accumulators provide sufficient energy to move the actuator to its fail-safe condition. The '990 patent replaces the membrane and nitrogen charged base accumulator with a spring-loaded piston accumulator. With the use of multiple accumulators built into the actuator, any accumulator can cease to function properly when required and the other accumulators will fully stroke the actuator/valve to its fail-safe condition.